This application is for a three-year competing supplement to Project #2-R01 ES008442-05 entitled Methyl Mercury Effects on Adolescent Development, underway in the Seychelles testing the hypothesis that adverse neurodevelopmental consequences of low-dose MeHg exposure will emerge in adolescence indicating latent or delayed MeHg neurotoxicity. This supplement will provide a unique opportunity to examine controversial issues related to MeHg exposure not included in the original grant (electrophysiological testing of auditory function, including brain stem auditory evoked potentials and evoked otoacoustic emissions, and cardiac autonomic function). These studies were not included in the original application because insufficient evidence existed at the time of the RO1 submission to justify their inclusion. Those circumstances have changed; supplemental funds are required to explore these issues. The electrophysiological endpoints will be added to the protocol being followed for the original R01 involving the Main Study cohort (n=779) which has been followed continuously since their births in 1989-1990. The supplemental project may provide crucial information about functions never before assessed in a population of children exposed to MeHg from fish consumption. Much of the evidence supporting adverse influences of MHg on brainstem auditory and cardiovascular autonomic functions is derived from studies of children whose mothers consumed whalemeat and whale blubber during pregnancy. Whales contain high levels of PCBs that could have caused the apparent neurotoxicity. Fish are high in micronutrients including PUFAs, which have been associated with enhanced brainstem auditory and cardiovascular autonomic functions. The proposed study will test the hypothesis that the brainstem auditory and cardiovascular autonomic outcomes in children whose mothers consumed a diet high in fish during pregnancy will be different than previous studies of whale-consuming populations have reported. This may be the last chance to conduct such assessments among the Seychellois children who are now reaching late adolescence. Public Health Significance. Fish consumption during pregnancy may pose a risk from fetal exposure to MeHg and a benefit stemming from its many micronutrients. This study will inform public health policy concerning the balance of risks and benefits of consuming fish during pregnancy with respect to cardiovascular health and cognitive information processing. [unreadable] [unreadable] [unreadable]